Abstract: In order to realize the synchronous secure encryption of two plains, the double image encryption algorithm based on discrete fractional angle transform and associated chaotic map. Firstly, the Coefficient matrix composite model was constructed based on discrete cosine transforms and Zigzag scanning and the two plains were merged into an image based on inverse discrete cosine transforms. Then the initial condition value was calculated by using the mean value of the pixel and the external key with coupling logistic map, and two random sequences were outputted by iterating this coupling map. The position array disrupt mechanism was constructed by sorting this two random sequences for scrambling compound plain. Then the scrambling compound was decomposed into two new components, and the two new components were fused into temporary cipher by combination the chaotic random phase mask generated by logistic map with modulated phase mask. Finally, the encryption model was designed based on the discrete fractional angle transform to change the pixel value of the temporary cipher for forming the cipher with a stable white noise distribution. The experimental results show that this algorithm had a higher security with stronger anti attack compared with the current dual image encryption technology.

Key words: Chaotic random phase mask